Late '36 hypoid rear end

[Steve9]

I'm just fishing among the '36 people to see if anyone has the late '36 hypoid rear end. A fellow '36 owner has been looking for decades and only found one and the guy wouldn't sell. The 3rd owner of my car located one in the 70's and installed in the car. The late '36 is unique because Dodge changed the size of their cars in '37, so the '36 hypoid remained an anomaly. All other earlier '36s came with the spiral bevel gears. If anyone has any info to further the subject, feel free to post. I wonder if these were prized and saved or just lost to the junkyards.

[R.White]

What's the problem with yours? Are you sure it's not just bearings and/or the crown wheel & pinion set up? I am just curious.

Ray.

[1936 D2]

I was not aware of this.

Can you tell from the outside which gear set is in there?

Are there casting series numbers in the differential that would indicate when the change was made?

Have you guys found any Serial Number cut off points for the spirals or dates that this change happened?

Would different editions of the Parts Manuals show this info?

Looks like the "36-42 Condensed Master Parts List" (pg 24 - with reference chart on pg 29) shows the "Rear Axle Housing" to be part # 651420 and the "Rear Axle Housing with Hypoid Axle" is part # 665276. The "pumpkin area " is the only thing different it seems. The axles themselves and all outer end bearings and seals seem to be the same.

Edited September 14, 2012 by 1936 D2 (see edit history)

[Steve9]

The difference is easy to see. The spiral bevel has the driveline and axle housings on the same horizontal plane. The hypoid has the driveline meeting the axle housing below the center point of the axles. An added benefit to this would be a lower driveline hump on later cars. All rear ends after '36 are hypoid, but the '37-'48 models are 3" wider than the '36 model. The '36 hypoid is a 10 bolt model and measures 52 inches between the brake backing plates. The '37-'48 is an 11 bolt with 55 inch spacing. I got this info from the afore mentioned friend. He took a '37 unit, had the axle housings shorted and installed the old '36 axles. Look up spiral bevel gear design on Wikipedia for more info on spiral bevel and hypoid.

[Steve9]

What's the problem with yours? Are you sure it's not just bearings and/or the crown wheel & pinion set up? I am just curious.

Ray.

Thanks Ray, No problems, just seeing if anyone else has this set-up too.

[1936 D2]

The difference is easy to see. The spiral bevel has the driveline and axle housings on the same horizontal plane. The hypoid has the driveline meeting the axle housing below the center point of the axles. An added benefit to this would be a lower driveline hump on later cars. All rear ends after '36 are hypoid, but the '37-'48 models are 3" wider than the '36 model. The '36 hypoid is a 10 bolt model and measures 52 inches between the brake backing plates. The '37-'48 is an 11 bolt with 55 inch spacing. I got this info from the afore mentioned friend. He took a '37 unit, had the axle housings shorted and installed the old '36 axles. Look up spiral bevel gear design on Wikipedia for more info on spiral bevel and hypoid.

Excellent info "Steve9". This will be important stuff for guys in the future working on their '36 Dodges!

[1936 D2]

So, this is a Spiral Gear rear axle?

And this is a Hypoid rear axle?

(This is a copy of the Build Record for this frame.)

And maybe this is a Spiral?

I guess I am the rare one. I have apparently NEVER PAID ATTENTION to the Hypoid or Spiral Geared rear axle thing! (Of course, I was never really looking!)

So these then are Spiral gears?

Edited September 17, 2012 by 1936 D2 (see edit history)

[jpage]

Just from curiousity I went out to check my diff and it is the standard rear axle. It has the six reinforcement flanges like the top photo fron 1936D2 and does measure 55 in. from plate to plate,it also has a 10 bolt pattern. I looked at my extra axle(maybe awaiting the junk yard) and to my surprise it must be an hypoid diff. It has only 4 reinforcement flanges, and the drive pinion enters on the lower left of the pumpkin below the center line! It also measures 55in. between plates and has a 10 bolt Pattern.It looks like the second photo in the above reply. I don't understand why one axle would be 3 in. narrower than another installed in the same car! What makes an hypoid rear better than a standard axle? If it's so much better I might use the hypoid instead. Or better yet,Maybe I can sell it and retire...HA ha!! If a guy can ask $500. for a window crank ,just think what an axle would bring..caching,caching!

[ply33]

... drive pinion enters on the lower left of the pumpkin below the center line! ... What makes an hypoid rear better than a standard axle?...

First part answers the second part. The main advantage of the hypoid rear is to lower the drive shaft so you can lower the floor of the passenger compartment more. Why they'd have had a mid-year shift from spiral bevel to hypoid doesn't make much sense to me as the advantage comes when you redesign the frame and body which they obviously did not do.

The hypoid is supposed to be quieter too but I've never heard a thing from the spiral bevel rear end in my '33 Plymouth so I don't know how that can be improved on.

[jpage]

I also found that I have a hypoid rear end from a '36 Dodge truck in 4:11-1 ratio, also 55 in. long. I'm not sure that they are so rare ,but if Steve9 didn't mention it I would probably not even noticed. Checked the tunnel height from both cars and no difference. If anyone needs a rear end for a truck or car let me know!

[1936 D2]

The interesting thing here is that the top photo in my #7 post is a Spiral Geared axle apparently, and that car was built June 5th, 1936.

The second photo of just the frame is a Hypoid Geared axle but that car was built five weeks EARLIER, on April 30th, 1936! Hmmm. :confused:

Edited September 17, 2012 by 1936 D2 (see edit history)

[1936 D2]

...The '36 hypoid is a 10 bolt model and measures 52 inches between the brake backing plates. The '37-'48 is an 11 bolt with 55 inch spacing. ...

So then "jpage", you actually have a '37-'48 Hypoid Geared axle if it measures 55" long.?. (Or what application rear axle would be 55" long with Spiral Gears?)

I find on my Spiral Geared axle car that there are some minor rubs from the tire on the INSIDE part, showing on the frame side of the fenders a bit and the frame itself from periodic side play of the axle housing. (It's those wild turns I make!) That must be from the narrower length of the '36 axle housing. So I wonder "jpage", does it seem like the rear tires on your car ride very close to the inside face of the rear outer fender panels? If that's the case I would think you would not be able to use "Wheel Shields" on your rear fenders because they would interfere with the wheels and hub caps.

Sounds like this may be why "Steve9" is finding the '36 Hypoid Geared axle (the 52") to be rather rare.

Edited September 17, 2012 by 1936 D2 (see edit history)

[jpage]

I don't know how close they fit as I've had the cars apart now for some time. I know that all three axles came with the cars and I suspect that they were original except the truck axle unless it may have been ordered specially for steep hilly terain.I don't know if that was possible but that car came from Kentucky. The spiral gear came from my first parts car that a friend had since the 1950's and he had never changed it.I believe it to be an early car as it had the 3 piece trim around the headlamp stands,a different fan blade and 2 flute door handles. The hypoid rear came from a car that only had 38,000 miles on it originally so I doubt that it had been changed. I measured from end to end of the axle housing to get the 55 in width. I didn't notice any clearence problems with any of the cars when they were together. I can't find any listing for an hypoid diff. in my parts book and no mention of differing axle lengths. If the hypoid axles are supposed to 55 in. why then is the spiral axle 55in. and why would a car built in April have the hypoid gear if they are only '37 and later? Were they a special order part? Were they a part that could be ordered in only certain parts of the county due to terain? 1936d2 ,do you know what gear ratio the hypoid rear is,I tried to take mine apart this afternoon but couldn't get the axles out! I still have a long way to go before I can see if the skirts fit! Did Chrysler narrow the axle width in '37 when they made some body changes,really can't see them mixing axle widths during a model year! Another mystery. Also 1936d2,remind me how you obtained your build cards,I might like to look into that!

[1936 D2]

My parts manual shows the actual axle parts (rods) to be the same in both Spiral and Hypoid versions for all '36 D2 cars.

It sounds as though, from "Steve9's" comments, that the '36 Hypoid axle housing is 52" - not 55". The 55" is for '37-'48 vehicles.

Looks like (in the "36-42 Condensed Master Parts List") that the Hypoid is ONLY 4.1 to 1. Drive gear 41 teeth and pinion 10 teeth. There are only two versions of the Hypoid axle gears for the '36 Dodge. One is identified as a set by "Generated" Gear and Pinion, have only one part number (because they came as a set only) and those were used in the D2 Sedans. The other were a separate Drive gear and Pinion gear with separate part numbers identified as "Formate" Type Gears and Pinions and are stamped as such on the parts. Those were used in the D2 7 Pass Sedan (Limo) and also in the D5-D8-D11-D14-D19.

This is the info I have from prior contact with the "Chrysler Historical Collection" in Detroit and the people I was corresponding with.

Chrysler LLC

Corporate Historical Collection

12501 Chrysler Fwy.

CIMS 410-11-21

Detroit, MI 48288 USA

Attn: Historical Information

Email: archives@wpchryslermuseum.org

Fax: (313) 252-2928

Walter P. Chrysler Museum Look under menu: Heritage - Chrysler Historical Services

And more specifically: Walter P. Chrysler Museum Archives

Information Request Form: PDF Document: Information Request Form

The person I was initially working with to get the copies of my records was:

Danielle Szostak-Viers /LCP/DCC/DCX

Edited September 17, 2012 by 1936 D2 (see edit history)

[jpage]

I just checked both hypoid diff. carriers and the carry the same casting number which is 665240-1. All three axle housings are the same except the rear cover on the 4:11 housing is deeper. The 2 hypoid carriers are the same except the 4:11 carrier has a bigger pinion oil seal and is stamped 4:11-0. None of the other 2 carriers are stamped with the ratio ,that I could find. It appears that the two diff.carriers were interchangeable with all but the 4:11 gear sets. They may have carried these over to later years using the same axle housing. I wonder if the narrower housing was for export units! If anyone has an export car maybe thay could measure their housing length and let us know! I'm not sure that Canadian built cars would fall into that catagory!

[Steve9]

Hypoid gears are stronger than bevel gears because the bevels load one tooth at a time and the hypoids load multiple teeth and move in a sliding or 'gnashing' action as the teeth slide against one another. Special gear lube must be used also because of the extreme pressure of this activity. Late '36 is just when Dodge changed, I wonder if other manufacturers did then too.

[jpage]

My parts catalog is dated March 16,1936 and makes no mention of any differential or axle change. It lists only 1 drive axle part number no.651675 and no 4:1 gear ratios . It does list a 4:125-1 ratio no. 651711 . It lists only 1 axle housing no. 651420 . It also shows the early 3 pc. headlamp trim so my one car with the spiral gear and 55 in. housing had to be built sometime before or around the printing of this catalog. If the hypoid appears on an April build card the change must have been soon after March not to have been included in the March catalog. If the hypoid diff. was to replace the spiral set you would think that it would have been included in the parts catalog as a replacement part and that you would see a regular production show up on cars built after April. I still think that they were only special order from the factory maybe for a specific purpose . Again all my axle housings are a 10 bolt pattern. Stated above that '37-'48 cars had an 11 bolt pattern. Also note that the inside wall of the tires measures about 2 3/4 in. from the frame at the shock location,of course this might vary given the brand of tire.

Edited September 18, 2012 by jpage (see edit history)

[bbbbbb9]

I just purchased a 36 coupe and it looks like it has one.

[jpage]

bbbbb9 ,If you can ,please measure the length of the axle housing (from the mounting flange where the backing plate fastens)to the other side. All mine measured 55 in. Everyone claims it should measure 52 in. Can't believe a car with 38,000 mi. would have an axle change, or all three for that matter!

[bbbbbb9]

The caar isn't at my house yet so it'll be a bit before I can get that measurement

[bbbbbb9]

The car isn't at my house yet so it'll be a bit before I can get that measurement

[1936 D2]

bbbbbb9 was asking in another thread for rear axle info. I had directed him to this post for the description info. I found some more photos in my stash of a hypoid rear axle (same car as the black painted frame above) and will post them here. (Two birds one stone!)

jpage: This car is in "deep dark storage" in another town for the winter so I would not be able to get that plate to plate axle measurement you were asking about. Sorry. bbbbbb9 will have to help you with that I think.

Edited November 7, 2012 by 1936 D2 (see edit history)